1. Field of the Invention
This invention relates to a temperature control system for a fuel cell powerplant of a separate cooling system. More particularly, the present invention relates to a temperature control system for a fuel cell powerplant of the kind wherein the powerplant comprises two or more fuel cell stacks and wherein cooling gas and process gases are separately fed to each fuel cell stack.
2. Description of the Prior Art
In a fuel cell system of the kind, fuel gas such as reformed hydrogen gas and an oxidant such as air are respectively fed to anode gas spaces and cathode gas spaces of each fuel cell stack and interact in the presence of catalyst to generate electric power. Since the fuel cell reaction is exothermic, it is required to cool the cell stack to maintain its operating temperature at the optimum value. For this reason, cooling gas such as, for example, air is supplied separate from the process air to cooling channels provided in each cell stack through respective circulating lines of the cooling gas. As a result of system design limitations such as geometric configurations, it has been considered to make common use of the cooling circulating line for all the cell stacks.
However, it has now been found that it is difficult to maintain the operating temperature of all the fuel cell stacks to the optimum value since an amount of the cooling gas supplied to each cell stack and an amount of heat generated by the fuel cell reaction vary from stack to stack.
It is therefore an object of the present invention to provide a temperature control system for a fuel cell powerplant of the kind that makes it possible to maintain the operating temperatures of all the fuel cell stacks to the optimum value.
Another object of the present invention is to provide a temperature control system for a fuel cell powerplant of the kind that makes it possible to make operating temperatures of all the fuel cell stacks uniform.
Still another object of the present invention is to provide an improved fuel cell powerplant with a long life and a high power output.